Question

According to an article from HuffingtonPost.com, some experts believe that 20% of all freshwater fish in the United States have such high levels of mercury that they are dangerous to eat. Suppose a fish market has 250 fish we consider randomly sampled from the population of edible freshwater fish. Use the Central Limit Theorem (and the Empirical Rule) to find the approximate probability that the market will have a proportion of fish with dangerously high levels of mercury that is more than two standard errors above 0.20.You can use the Central Limit Theorem because the fish were randomly sampled; the population is more than 10 times 250; and n times p is 50, and n times (1 minus p) is 200, and both are more than 10.